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Arctic Sea Ice

The North Pole does not move, but the comparatively thin ice floe is moving like a film of cream on milk. The images below show the extent of the Arctic sea ice on two different days. Click on either image to see an animation of the sea ice day to day from September 28 2003 to May 10 2004. (The file is 21MB)

The gray areas are ice. Darker gray indicates older ice. The wispy white areas are clouds. The black dot is centered on the North Pole. There is no data for that area.

September 28, 2003

May 10, 2004

Animation courtesy National Oceanic and Atmospheric Administration.

For more information about how this animation was made visit the Sea Ice Animation web page.

Freezing Sea Water

Saltwater has a much lower freezing point than freshwater does. The more salt there is in water, the lower the freezing point gets. In order to know the temperature at which saltwater is going to freeze, it is necessary to know how salty the water is. For fresh water the freezing point is 0°C. For saturated saltwater, which is 23.3% salt by weight, the freezing point is -21.1°C. Salt water with a salinity of 35,000 ppm (parts per million), which is the average salinity of the open ocean, freezes at about -2° C. As sea water freezes, the salt becomes more concentrated in the remaining unfrozen water. This is because the salt is forced out of the ice as the water freezes. The ice is composed only of water. The salt goes into the surrounding water. This makes Arctic water extremely salty, more so than most of the world oceans, causing it to freeze at a lower temperature.

Here we can see different types of ice.

Ice

Eskimos have dozens of terms for snow just as farmers in Southeast Asia have two hundred words for rice. Similarly, Russian seafarers have many words for ice. This is a concern for them today since some computer models predict that by 2080 the arctic ice cover will completely disappear in summer. There will be no need for an icebreaker. It will then be possible to sail or row your way to the North Pole. Today, ice starts with frazil or grease ice. In quiet conditions, the frazil crystals soon freeze together to form a continuous thin sheet of young ice. When it is still transparent, it is called nilas. When only a few centimeters thick it is transparent and is called dark nilas. As the ice grows thicker the nilas takes on a gray and finally a white appearance. Once nilas has formed, a quite different growth process occurs, in which water molecules freeze on to the bottom of the existing ice sheet. This growth process yields first-year ice. If the ice survives a summer, it builds up as multiple-year ice.

Icebergs

Icebergs are created on land, from glaciers. The snow falls in a valley, and after many years it becomes ice many meters—sometimes tens of meters—thick. The glacier then moves toward the sea where parts of it break off, or “calve” into the sea. These broken parts of the glacier are icebergs. The arctic ocean is far from the land, so it is unlikely that icebergs would drift up toward the pole. During our two-week trip, we saw only one iceberg, and it was a tiny one, only fifteen ft. tall—a dwarf as compared to the ones seen on the Antarctica coast. The Titanic would have been safer if it had been a bit closer to the arctic ice pack!

Icebreakers

Fram

Fritjof Nansen used the Fram, a ship with a reinforced hull. He let it drift up to 85° N. The  Fram built in 1892 weighed 402 tons and had engines of 220 horse power.

Yamal

The Yamal, the ship we used to go to North Pole, is the last of the Arktika type nuclear icebreakers. It was built in 1992 and supplies an impressive 75,000 hp. The sister ships are the Arktika, the Rossiya, the Sibir and the Sovyet Skiy. It has a draft of 11 m (36.24 ft). The hull has a thickness of 4.8 cm. It has a capacity of 23,000 tons. As a comparison, the Queen Mary 2, the recently launched cruise-liner has a record-breaking 157,000 hp, more than twice the Yamal capacity, but it weighs 151,400 tons, more than six times the Yamal weight.  The Yamal can break ice 4 meters thick like butter and has been successfully handling ice ridges of up to 9 m.

Independently of the figures, watching the Yamal working on a 10 m-high ice hummock is just beyond imagination. The whole ship vibrates under the effort. Huge blocks of ice are pushed away and behind. 

Nautical Units

Nautical mile

The nautical mile was historically defined as a minute of arc along a great circle of the Earth. It can therefore be used for approximate measures on a meridian as change of latitude on a nautical chart. However, like all planets, the earth is not a perfect sphere. It bulges at the equator like a spinning top, so the length of one minute of arc on the Earth's surface varies from 1843 m at the poles to 1862 m at the Equator. The international standard definition is: 1 nautical mile = 1852 m.

What’s behind a minute?

Onboard the Yamal, we were sometimes joking that we were only twenty minutes from the North Pole. We were meaning twenty minutes of angle, not twenty minutes of time. Twenty minutes of angle makes twenty nautical miles. At two knots, this takes ten hours or 600 minutes of time:

In other words:
        20 minutes (angle)  = 600 minutes (time)

Knot

In some sailing ships, speed was measured by casting a log from the stern. The log was relatively immobile, and attached by line to a reel. Some sources suggest that knots placed at a distance of 47 ft 3 in (14.4018 m) passed through a sailor's fingers, while another used a 28 second sandglass to time the operation. The knot count would be reported and used in the sailing master's dead reckoning and navigation. Today, one knot is exactly one nautical mile/h or 1.852 km/h.

Penguins

You are not likely to see penguins at the North Pole, unless you have brought them with you on the icebreaker. The Northernmost habitat for penguin is the Galapagos islands, close to the equator. They all live in the Southern Hemisphere.

Polar Bears

Polar bears

The fauna around the pole is extremely limited. Water tends to freeze very easily, so fish and sea lions are not getting close to surface. Polar bears feed on sea lions and you can find some at the edge of the ice pack, but not close to the pole. We were lucky to see several families of females and cubs. One bear successfully hunted a sea lion. The other bears were trying to rob the hunter of his prey.